{"blocks": [{"key": "c49e6daa", "text": "Scenario", "type": "header-two", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "25d4596d", "text": "You are asked to architect a full-funnel advertising platform that serves personalized ads to users on a social media app.", "type": "unstyled", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "5fad4120", "text": "Question", "type": "header-two", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "aec8e0a9", "text": "Design an ads serving system end-to-end. Cover data collection, feature engineering, model choice, real-time ranking, feedback loops, and A/B evaluation. What offline and online metrics would you track and how would you handle cold-start users?", "type": "unstyled", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "cfab7419", "text": "Hints", "type": "header-two", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}, {"key": "531a27bd", "text": "Think retrieval → ranking → re-ranking, latency budgets, feature stores, and exploration/exploitation strategies.", "type": "unstyled", "depth": 0, "inlineStyleRanges": [], "entityRanges": [], "data": {}}], "entityMap": {}}